Assassination Classroom- Blue Viper
by Lucifer Morgenstern -PoD
Summary: Nagisa. Shy, quiet and girlish. Blue Viper. Dangerous. Smart. Open. Nothing seems similar. But appearances can be deceiving.
1. Introduction

**This is my new AssClass series. Credit to Zane Alias for co-writing. Though this chapter has NOTHING written by him.**

To the outside world, Nagisa is a shy and quiet student. A bluenette with with a girlish build, with okay grades. He is in the class 3-E. Nagisa sighed. Another boring day. Yukimura Aguri, the teacher of this class had gone missing. It has been almost a week. Class was almost over. Time to go back to an abusive, mental mother. An abusive mother that he could do nothing about. Well, won't do anything about. The substitute droned on and on about The Battle of Nagashino.

11:46 PM. A shadow ran across the rooftops of a series of high rises. A ledge appeared and he dropped down silently. Pushing open a window, he jumped in. A second later, 2 muffled thumps. Splattered blood on the window. "Who's there?"

"No one."

A gasp. "Blue Viper!"

A smirk. "So you know me?"

"Who do-doesn't?"

"Well. Then you know what I must do. Don't you?"

"Please. NO! SPARE ME! SPARE MEA AHHAHHHHHHHHHH!"

Slice. Blue Viper camly wiped off any blood as the body fell and then left his signature mark. The burn mark of a viper. Exiting the room, he closed the window, climbed onto the roof, and went back the way he came. Another success.

 **Just a little intro. Nothing more. The content comes later. Be patient. BTW, when I do A/Ns, they will be bolded. When he is doing them, they are underlined and italicized.**


	2. Enter Koro Sensei

The moon blew up. Simple as that. A dark matter implosion shattered seventy percent of the moon. Already, this mysterious phenomenon was causing panic. But that wasn't it. The shutter door opened and people with suits came in. They introduced themselves as government agents with the Ministry of Defence. A yellow, humanoid tentacle creature followed them in. And they told the kids to kill this creature. _Way to put it bluntly Karasuma_ , Nagisa thought with a raised eyebrow as everyone else sweatdropped. Nagisa then turned his focus to the yellow thing. _He seems familiar somehow. I feel like… I feel like I've met him befor… huh?_

This yellow thing was staring at Nagisa. A sort of a sad expression, hidden under his mask of a wide smile. Immediately on guard, Nagisa dropped his hands. His body was read to spring at any moment, but most people couldn't tell as no where on his body indicated any tension. But that sad expression was gone, replaced by… _pride? The hel- No… No way…_

The split second of shock that was quickly wiped off was not unnoticed by the yellow thing. His smile grew wider. _No way… Is.. is that?_

Night fell. Nagisa waited an hour after his mother went to bed, his face still stinging from a slap he received for being late. Quickly changing into gear, it was Blue Viper that emerged from his window. Not Nagisa. Quickly racing to the school, he found a shadow looming from the top of the building. "Hello Nagisa."

"Is...Is that really you?"

"Hmmm. Is that?"

And a second later, he appeared behind Nagisa, holding the knife he threw just a second before. "Not bad. Your reflexes have improved while I was gone."

"It is you." Nagisa whispered.

"Yes."

"Welcome back Reaper-Sensei."

 **Did you like that? Or did you think this came to early? Eh? Post reviews. This plot twist (Can we even call it that?) was expected or no? Also, again, Zane did nothing. Also, the title for this chapter really plays in the NEXT chapter. So..**


	3. Class Time

**Eh. I don't know what to say. Um… I guess… Zane is finally writing? Yay? Also, grammar mistake last chapter. The sentence "'Hmmm. Is that?'" is supposed to be "'Hmmm. Is it?'" *Cue Music* I'M ONLY HUMAN AFTER ALL!... or… am I?** _Cue dramatic sounds._ **Don't forget that the underlined and italicized words are Zane's author notes.**

One by one, students field into the classroom, monotonically shuffling to their individual desks, giving off an aura of listlessness and basic sadness. A second later, the door opened and the yellow creature from before slid up to the front, picking up the roll sheet. Everyone eyed him. Completely ignoring this, he announced, "All right class. When I call your name, tell me that you're here. Yuma?"

However, it was Nagisa that stood up before Yuma, in his raised hand was a government-issued pistol, which he fired from while this being as the thing was preoccupied with the clipboard he was clutching. Being slightly flustered, he immediately deflected the shot with the clipboard as Nagisa emptied his clip before lowering the board and turned back to Nagisa. "Tsk, Tsk Nagisa. To slow. Nururufufufu."

Nagisa rolled his eyes, glancing at the people staring at him. "What?"

"Nothing. It's just that… you're usually not this… composed?" Yuma said.

Nagisa just looked at him.

"Well, there's a lot of things you don't know about me Yuma. Plus, killing him IS our top priority."

Raising an eyebrow and wondering if Nagisa was always like this, Yuma stood up with a Minebea P-9, modified to shoot BBs. "Speak for yourself."

On cue, the whole class got up, whipping out throwing knives and firearms to try to blast Korosensei into oblivion. But alas, due to the class's horrible aim from their lack of training and the speed of the creature, the class failed to land a single shot. Everyone was panting from exertion and frustration apart from Nagisa, the kids looked on in awe and anger as this thing stood unharmed.

"I can't be killed that easily, you'll find." the thing gloated.

"But these are just plastic BBs. For all we know, you just took 'em like a champ."

He sighed, scanning the room's floor that was covered in BBs. "Collect all of the BBs and bring them here."

As the class went about cleaning up the mess, the thing plucked the pistol out of Sugino's hand, aiming it at himself.

"As you can see, the BBs do nothing to you. However…" It fired the gun upon his own tentacle arm, instantly severing it with a pop. "...The BBs can cut through my cells like a knife through hot tofu." he concluded, the class's face watched in horror.

Nagisa had eyebrows raised at that sight. Nakamura then spoke up asking, "So what do we call you? I mean, we can't just keep calling you Weird-Yellow-Space-Tentacle-Monster-Thing-Sensei can we?"

"Yeah, that's true. Hm. I guess I will just let the class decide this then. Nururufufufu."

"Um. Well, Korosa Reni means 'Can't be killed' and 'Sensei' means teacher. I guess we can call you 'Koro Sensei'. It's accurate and also a play on words." Kayano said.

The class started muttering to each other, saying things like "Yeah, I like that."

"Koro Sensei eh? Hm. So that is what you will call me now. Nururufufufufu!"

As the class filed out at the end of the day, Nagisa stayed behind. "So. Koro Sensei. Not ."

Korosensei's smile widened as he slithered out of the classroom, Nagisa following close behind. "Sir, may I ask what has happened to you? You've changed a lot in the short span of a year."

"Well, a lot of things can change in a year. That's 12 months, 52 weeks, 365 days, 8,760 hours, 525,600 minutes, or 31,536,000 seconds. And I will tell you. Just not today."

"But why? I mean, you just left me and then a year later, you turn into this."

"I know. But I just can't tell you…"

"Can you at least tell me why you wanted to teach?"

"...I… maybe another time…"

Right when Korosensei finished speaking, Nagisa whipped out one of his rubber knives. Korosensei flinched away, sure that Nagisa was going to slash him, only for Nagisa to throw it behind him, bouncing off a nearby door."I know there's someone behind that door. Come out."

Kayano sheepishly stepped out from her hiding spot, a little bit flustered at Nagisa's amazing hearing."Kayano? What're you doing here?"

"I just saw you walking with Korosensei. I was going to leave, but I heard you say 'what has happened to you?' So you've met him somewhere before?" Kayano whispered.

Nagisa's composed look slipped for just a second, showing a mix of bewilderment and surprise. _Damn it! How did I not notice!?_ "I don't know what you are talking about. Now, if you'll excuse me, I should probably go home soon."

Nagisa left the two behind in the dust, as he ran off to whatever his next destination was.


	4. Assassination Attempt K

**A chapter showing two skilled assassins, and one with the power to go Mach 20. Let the killings begin.**

Two figures, one tall, the other about have his size, was silhouettes on the tallest building in Tokyo. They stood upon the roof, eyeing the inhabitants scurrying around below, calling or texting or just enjoying the lights."Let's begin, shall we?"

"Yes, senpai."

They jumped down the Toranomon Tower into the city street below. Nagisa was wearing a Black Ops Stealth Glide Suit XG-h II, courtesy of the black market. The wind and thrusters helped him maneuver quietly across the sky next to the flying Koro-Sensei. Though on the outside it seemed like Nagisa's family had a middle class income, Nagisa was wealthy. He was an assassin for hire, and he got payed a lot. The highest he got during his year was 100,000,000,000 yen. He just never showed off his wealth. Well, when he was Nagisa anyway. When he was Blue Viper, he bought food, weapons, hotel rooms, companies, and all kinds of other stuff. Of course, none of the money went to personal items. Only what was needed for assassination.

Who was their target? A man named Tadaomi Karasuma. The Air Force Elite Soldier was guarding the meeting of high JSDF officials in a penthouse. Nagisa scoffed. _A penthouse. Really?_ "Nagisa."

"Hm?"

"Remember. They can't see me. After we get inside, you're on your own."

"That's fine Senpai. Really."

"Look at you. All grown up."

Smiling, Nagisa and Koro-Sensei landed on the roof. Two guards, unaware of their presence, stood at the roof exit. A spotter and sniper on all four sides. Turrets and their operators on each corner. _Must be some pretty high up people in their. If that's so, then why were we only tasked with killing Karasuma? We could cause so much more damage if we killed the people inside the room._

A man named Takaoka said if he killed Karasuma, he would get 20,000,000. If he just wounded him, 5,000,000. His identity was supposed to remain secret. Nagisa always kept his honor on his Assassin-Client privilege code. Not wanting to alert the rest of the guards, Koro-Sensei raced Nagisa in and raced out in the span of .00003 seconds. The guards looked a bit bewildered and confused at the sudden force of wind but otherwise seemed relaxed. _Nururufufufu. Relaxed. Just you wait._

Sneaking into the corridor of the penthouse, Nagisa aimed a dart at the man next to Karasuma. A tiny _Pstsh_ and the dart was off. The man jerked and fell as Karasuma instantly drew his gun. _I can't let that fire. If it does, then everyone will be alerted. I mean, I could take them but Takaoka said not to harm anyone else._

All of Nagisa's assassinations involved the victim seeing his face right before his death. Not wanting anyone that might've lived to see his face before they died, Nagisa wears a mask. Karasuma didn't know that it was Nagisa. All he knew was that it was Blue Viper calmly walking out of the shadows, the top half of his face covered and only showing the cynical smile. The most dangerous assassin next to Reaper himself.

Karasuma raised his gun but dropped it as a knife sliced the back of both hands. _So fast!_ he thought as Nagisa rushed at him. "Blue Viper, you will not disturb this meeting!"

The shout was not heard over the sound of JSDF officials and politicians arguing. "Oh no. My target is you."

This stunned Karasuma for a second as he faltered, a bit confused. Then he raised his arms to block the roundhouse kick headed toward his head. But as he was distracted by this distraction, Nagisa twisted his body and sunk a knife into Karasuma's side. Karasuma grimaced but stood strong. He grabbed Blue Viper's leg, only to be kicked in the abdomen but the other. Then a stab in his back and a slice at his throat.

He fell. Nagisa flipped the mask open to reveal those cold and blue eyes. Karasuma's eyes widened and just as he raised the knife, the door banged open. A JSDF officer yelled, "God damn these politicians! If they-..."

He started at Blue Viper and Karasuma's dying body. Bullets reached for Nagisa but Nagisa ran. Up the stairs. The guards up above were warned and they readied to shoot but got knocked out at they turned to late and got kicked in the face with a split kick. Then he jumped off the roof and away he went.

If was school again. Karasuma drove painfully to the parking lot and limped up too 3-E's classroom. And he opened the door. "Ohayōgozaim-"


	5. Sorry

**Hey. Sorry for the lack of updates. School and Homework have got me, plus I am also trying to further lengthen the plot of this story. Please do not stop reading for the lack of chapters. I am trying. I hope you understand.**

-Shattered Reality


	6. Surprise

**Finally! I started high school recently and the summer was full of stuff to do. I hope this update pleases all of you that still follow the story. Thank you for the… support?**

Karasuma started. He was unable to process what he sees. That blue hair and those blue eyes. What was full of bloodlust just yesterday, stared at him with pure child innocence. _BAKANA! It can't be! I have the Blue Viper as my student?_

With the same innocence in his face, Nagisa asked Karasuma, "Are you alright, sir? You look like you've seen a ghost."

Next to Karasuma, Korosensei laughed a very knowing laugh. "Welcome Karasuma-san ( **He did call him that right? Bit rusty.)** Come on in!"

Karasuma still stayed where he was. His JSDF and Air Elite soldier kicked in as Karasuma was suddenly next to a surprised Nagisa. "Wha-" Nagisa managed to get out, before getting grabbed by the throat and slammed face first into the ground, one hand pinned, the other twisted, with Karasuma knee at his neck.

Nagisa suppressed a smile. He couldn't reveal who is was now. It was too soon. Sounding scared and surprised, he yelped.

Korosensei was next to him in a flash, and the weight on his back was suddenly lifted. "Ah ah ah! Karasuma-san, I cannot have you harming my students. Calm yourself and explain your actions."

Karasuma dusted himself off and took a breath. Inside his mind, he argued with himself. _He is a dangerous criminal. However, I have no proof. My actions here would get me investigated. But, that could get him investigated too. For now, I need to make something up._

"You were caught by surprise. This shows your… inexperience. I move so much slower than that of this octopus. If you cannot even catch this, you have no hope of saving this world. I did that to assess the skills of this class."

"Oh? Then what of your initial reaction when entering this class?"

Karasuma gritted his teeth. He stared at Nagisa as he shied away, a scared look on his face. He frowned. "That is not something that you need to care about."

"I think it is. He is, after all, my student."

As Karasuma opened his mouth to answer, he felt his skin crawl. As if a snake of coiling around him. He felt what it meant to die. Whirling around, he saw that Nagisa flashed him a quick smile. _IT IS HIM!_

Karasuma lunged towards Nagisa, but Korosensei grabbed him and pulled him back, putting his messed up hair back to its original glory. "I can't have you attacking my students Karasuma-san. It doesn't matter if you are from the Ministry of Defence. Your boss will hear about this. Out!"

Karasuma was then frog marched towards the door, glaring at Nagisa the entire time. He still was when the sliding door slammed. "What do you think he wanted, Nagisa?" Kaede asked him in a small voice.

"I.. I don't know. Thank you Koro Sensei." Nagisa replied.

Suddenly, Tomohito rushed up to Korosensei with a rubber knife and slashed at thin air. "You have to be faster than that Sugino-kun," he laughed.

For the rest of the day, Karasuma watched Nagisa from a tree nearby. Every now and then, Nagisa would give him a wave that would always make Karasuma's heart clench.

 **And that is it! Sorry for the short chapter. This was made in about 10 minutes or so. What do you want to happen? Tell me with reviews, gimme your thoughts, hell, even make OCs to be added. But of course, the OCs have to play a part. No more powerful that Korosensei or Nagisa. For now. Thanks and goodnight. Maybe another part to this story later tonight, but most likely not. Check my other AssClass story for an update later.**


End file.
